# Ordinal Data - Sorting (Problem / Algorithm)

## About

- Input: array of n numbers, unsorted.
- Output: array of n numbers, sorted (from smallest to largest)

Possible Assumption:

- numbers are distinct
- with duplicates, the problem can even be easier

Sorting has complexity O(n log n) but repeated sorting can be avoided with a better data structure

## Articles Related

## Illustration

Manual sorting and counting of 4 million London Underground tickets in 1939 to analyse train use across the network.